package com.micro.commonutils.util.jwt;

import java.io.DataInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.security.*;

/**
 * @Author Reyna.chen
 * @Date 2022/1/6 9:56
 * @Version 1.0
 * @Description:
 */
public class RsaKeyHelper {

    /**
     * 获取公钥
     */

    public PublicKey getPublicKey(String filename) throws Exception{
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(filename);
        DataInputStream dis = new DataInputStream(resourceAsStream);
        byte[] keyBytes = new byte[resourceAsStream.available()];
        dis.readFully(keyBytes);
        dis.close();
        X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
        KeyFactory kf= KeyFactory.getInstance("RSA");
        return kf.generatePublic(spec);
    }

    /**
     * 生成私钥
     * @param filename
     * @return
     * @throws Exception
     */
    public  PrivateKey getPrivateKey(String filename) throws Exception{
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(filename);
        DataInputStream dis = new DataInputStream(resourceAsStream);
        byte[] keyBytes = new byte[resourceAsStream.available()];
        dis.readFully(keyBytes);
        dis.close();
        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(spec);
    }

    /**
     * 获取公钥
     *
     * @param publicKey
     * @return
     * @throws Exception
     */
    public PublicKey getPublicKey(byte[] publicKey) throws Exception {
        X509EncodedKeySpec spec = new X509EncodedKeySpec(publicKey);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePublic(spec);
    }

    /**
     * 获取密钥
     *
     * @param privateKey
     * @return
     * @throws Exception
     */
    public PrivateKey getPrivateKey(byte[] privateKey) throws Exception {
        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(privateKey);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(spec);
    }

    /**
     * 生存rsa公钥和密钥
     *
     * @param publicKeyFilename
     * @param privateKeyFilename
     * @param password
     * @throws IOException
     * @throws NoSuchAlgorithmException
     */
    public  void generateKey(String publicKeyFilename,String privateKeyFilename,String password) throws IOException,NoSuchAlgorithmException{
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        SecureRandom secureRandom = new SecureRandom(password.getBytes());
        keyPairGenerator.initialize(1024, secureRandom);
        KeyPair keyPair = keyPairGenerator.genKeyPair();
        byte[] publicKeyBytes=keyPair.getPublic().getEncoded();
        FileOutputStream fos = new FileOutputStream(publicKeyFilename);
        fos.write(publicKeyBytes);
        fos.close();
        byte[] privateKeyBytes=keyPair.getPrivate().getEncoded();
        fos = new FileOutputStream(privateKeyFilename);
        fos.write(privateKeyBytes);
        fos.close();
    }
}
